Abrasive articles used in polishing or grinding operations are generally expected to perform their abrasive function with a high degree of precision. However, the abrasive manufacturing process has been known to provide similarly constructed abrasive articles that differ from one another in their performance characteristics. In part, this variability may be caused by variability in the quality and characteristics of the raw materials used to make the abrasive article. Hence, variation in the performance of abrasive articles is an inherent result of the manufacturing process. Moreover, manufacturers of abrasive articles often define their product specifications in a manner that allows for performance variations while providing satisfactory product yields. These variabilities in abrasive articles make it difficult to predict the specific performance of an abrasive article in a particular application even in those cases where the abrasive article is a replacement part for a similarly constructed abrasive article used in the same polishing or grinding process.
Traditional off-hand grinding or polishing processes are normally judged as complete when a desired amount of material is removed from a work surface or when the desired surface finish is attained. The end point of the process may be determined after multiple measurements have been taken at successive intervals during processing. It is becoming increasingly common to replace such off-hand grinding/polishing processes with automated processes that require preset process conditions in the finishing of successive workpieces, and it is desirable to provide abrasive articles in a manner that allows for the adjustment of process conditions prior to the initial use of an abrasive article.
Because of the variations inherent in abrasive article manufacturing, processes using abrasive articles often require an adjustment to the process conditions when the abrasive article is replaced in an existing process line. Changes to such process conditions might include, for example, the pressure at which the abrasive article is applied to a work surface, the contact time or the speed of the abrasive article (e.g., centimeters per minute, rotations per minute, etc.) relative to the workpiece. These adjustments to abrasive process conditions have contributed to lower productivity and higher costs because new process settings have traditionally been determined only after a new abrasive article is inserted in the process line and the performance of the article has been initially observed under the process settings used for the previous abrasive article. This adjustment method can require significant time and effort, and it may cause damage to one or more workpieces during the recalibration. Abrasive process conditions are then adjusted to accommodate the new abrasive article only after the performance of the new article has been observed at least once within the same process line.
Although improvements are needed and desired in the predictability of abrasive performance, new or replacement abrasive articles still require a trial and error evaluation prior to their actual use in an abrasive process line. While manufacturers have marked their abrasive articles with indicia to indicate abrasive grit composition, size, and the like, the abrasive art has failed to develop methods for the manufacture of an abrasive article wherein the article is labeled with a performance index that can be used by an end user of the article to adjust the initial process conditions under which the abrasive article will be used.
The creation and use of a performance index addresses a long felt and unsolved need by providing a means by which the end user of the abrasive article can adjust the initial process conditions prior to the initial use of the abrasive article.